In all my years of battling I never paid enough attention to this, but now I forget how it works and am stuck with some team making.

Now, does Air Lock (and Cloud Nine) actually stop the weather or just the effects while the Pokemon with the ability Air Lock/Cloud Nine is in play?

For example:

Foe has Kyogre on first turn, you have Charizard. For some reason you feel Charizard can't beat Kyogre, so you switch out to Rayquaza. Now, the guy switches out his Kyogre, sends in a Mamoswine, KOs the Rayquaza. Does he have to send out Kyogre again or is the Rain back on?